A security module is understood to mean a smart card with contacts serving to control data transfer towards a receiver. The security module, connected to the receiver, is in general removable. It serves to verify the authorization of data processing by supplying the digital keys necessary for the functioning of the receiver. The smart card can notably have dimensions defined by standards ISO 7816 or be of a more reduced size similar to that of a SIM card, particularly used in mobile telephones.
For example, a Pay-TV decoder is equipped with a security module in the form of a smart card. The role of the decoder is to decrypt an audio/video digital data stream according to the rights granted to a subscriber stored in the security module. The data stream can only be decrypted if these rights are valid. More precisely, decryption is carried out when the key contained in the module is valid and allows the decryption of the control words CW contained in the control messages ECM accompanying the data of the stream.
In certain applications, the security module is intended to be definitively inserted into an apparatus, in theory without ever being removed from the apparatus thereafter. In the case of apparatus maintenance or repair, a change of security module will then be carried out under the control of the organization having delivered the module. This is the case, for example, with Pay-TV decoders, where a decoder is supplied to a user at the same time as a security module in the form of a chip card of various dimensions.
In this type of context, two cases are possible, namely:                the user must introduce the module in question into the decoder once. In this case, it is usually not necessary to extract it.        the security module is irreversibly introduced into the decoder during manufacture without even the user being informed that the decoder contains a module which must be extracted only by an authorized person.        
In general, a decoder is supplied under the conditions of the first case, since the majority of the security modules originate from a different source than the decoder itself. The latter is equipped with standardized connection means, accepting the security modules in the form of ISO 7816 format chip cards or SIM cards, which allow easy module insertion by any user.
Therefore, it is also easy to withdraw the cards from the socket or acceptor in which they are connected by exerting traction on a part of these cards. This kind of manipulation is not in general desirable and furthermore not authorized by the organization or the operator supplying charged decrypting rights. In fact, the operator wishes to avoid the exchanges of security modules from one decoder to another or the replacement of the module by a third module.
A known method for averting the unauthorized withdrawal of a security module is to mechanically block the latter in the acceptor and if extraction is attempted, the blocking means or the manipulation of the acceptor provoke the destruction of the module. Patent application WO 01/39101 describes connectors for security module acceptors provided with different blocking and destruction means such as:                blocking by an instantaneous adhesive discharge at the point of insertion of the module into the connector.        destruction by subjecting acceptor contacts to high electrical voltage or localized heating to high temperature of the module during an extraction attempt.        blocking of the module by anchorage points in the connector which retain the previously weakened module by means of grooves on its surface. Withdrawal leads to its mechanical destruction.        
The common factor in the irreversible insertion devices of security modules described above is the destruction of the module in the case of withdrawal. Furthermore, in certain cases, it is even not possible to re-insert a new module into the acceptor since the connector is also damaged, particularly in the case of blocking by adhesive or in the case of destruction by electric or thermal action.